Optical films can be utilized in a variety of applications. These films sometimes can employ a thin metal layer e.g., silver. Optical films can be used in various constructions on supports such as glass or flexible substrates for a variety of purposes such as in solar control films, EMI shielding films, window films, and conductor films. These films can have high visible light transmission, and if metalized, low electrical resistivity.
There is a proportional relationship between optical transmission and resistivity in metal, e.g., silver. This relationship makes the typical objective, forming a film having both high visible light transmission and low resistivity, a delicate balance because changing the performance of either property can adversely affect the other. When forming a metal layer, the metal can agglomerate as it is deposited. This can result in a film that is not homogeneous, and can require application of a relatively thick layer of metal to provide an effective shielding film. This agglomeration or formation of islands makes the optical transmission diminish and causes an increase in resistivity.